Is European Union law a fully self-contained regime?: a theoretical inquiry of the functional legal regimes in the context of fragmentation of international law

The fragmentation of international law has led to the emergence of specialized and (quasi) autonomous legal regimes - the "self-contained regimes" or special regimes. This article aims to investigate the degree to which European Union law could be a potential candidate for a "self- contained regime" and questions the relationship between this special regime and general international law. The methodological approach consists in providing a critical analysis of the Report on Fragmentation of International Law of the International Law Commission, concluded in 2006 and the ECJ case law in order to identify and explain pro et contra arguments regarding the following assertion: although EU law is not totally decoupled from general principles of international law, the new legal order of the EU has taken a historical turn towards self- containedness. Embracing the European legal perspective, this inquiry will advocate a presumption in favor of the self-contained character of the EU legal order, based on the EU sui generis modus operandi, the establishment of its own constitutional legal order, accommodating its own norms, techniques and features of modern law-making within its sphere of application, albeit the possible fallback on general international state responsibility and countermeasures mechanisms in case the mechanisms inherent in the EU system fail